The no-frills pricing begins at £25 per month. You can choose from 12- or 24-month contracts, all of which come with 5,000 texts, 1GB of Internet data and free unlimited access to BT Openzone Wi-Fi.
Up-front prices for the phone itself start at £50, or you can get it free on a £45 per month, two-year contract. See how Tesco stacks up against O2, Orange, Three, T-Mobile and Vodafone in our up-to-the-minute iPhone 4S price comparison.
We're impressed with Tesco's prices, especially the 12-month deals. They're not only cheaper than any of the other networks by total cost, they're even cheaper than buying an unlocked 4S and putting a Giffgaff SIM in it, previously the cheapest option by a country mile.
Giffgaff offers unlimited data over 3G, but Tesco offers unlimited Wi-Fi when you're out and about. It's six of one, half a dozen of the other -- adding up to a great deal for you. Both networks use O2's signal, so if O2 reception is decent round your way these are seriously bargainous options.
The iPhone 4S hits shops tomorrow. Tesco is worried about having enough phones to meet demand, so it's promising you Clubcard points if you have to wait for your new phone -- 500 points for existing Clubcarders who have to wait a fortnight, and 1,000 points for Clubbers who still don't have their phone a month from now.
Are you tempted by Tesco's no-frills prices? Tell us your thoughts in the comments section below or on our Facebook page.